Inspection hole in turbomachine casing and plug

ABSTRACT

An inspection hole and plug are provided for an outer casing of a turbomachine. The plug includes an attachment portion configured to removably attach the plug to a coupling portion of the inspection hole. Additionally, the plug includes a tightening portion, a lock nut, and a rod extending through the plug. The lock nut is configured to removably attach the rod to the tightening portion of the plug. The rod also extends into a body of the inspection hole. Further, the inspection hole includes a stepped end positioned proximate to an inner surface of the outer casing to prevent the rod from extending through the outer casing of the turbomachine.

FIELD OF THE INVENTION

The present disclosure relates generally to an inspection hole in a casing of a turbomachine and a corresponding plug for said inspection hole.

BACKGROUND OF THE INVENTION

Industrial and power generation turbomachines generally include a compressor, a combustor assembly, and a turbine. The compressor and turbine are enclosed within a casing. The compressor receives ambient air, compresses the air, and then flows at least a portion of the compressed air to the combustor assembly. The combustor assembly combusts a mixture of compressed air and fuel to produce hot combustion gasses. The combustion gasses then flow through one or more turbine stages to generate power for a load, a compressor, or both.

The compressor and the turbine include a plurality of stationary and rotary components. For example the compressor includes a plurality of rotor blades configured to rotate about a shaft, and a plurality of stationary stator vanes. Similarly, the turbine includes a plurality of rotor blades configured to rotate about the shaft and a plurality of stationary stator vanes. Over time, the various components of the compressor and/or turbine of the turbomachine may wear or develop defects. Inspection of these components to determine wear and/or defects may be difficult due to the enclosure of the compressor and turbine within the casing.

One technique for inspecting the internal components of the compressor and turbine is by inserting a borescope through a borescope hole in the casing of the turbomachine. During operation of the turbomachine, the borescope holes may be closed using a plug so as to prevent the escape of compressed air from the compressor or combustion gasses from the turbine. The plugs may be positioned within a counterbore area that allows the plug to be positioned below the surface of the casing. In addition, certain of the plugs may leave a majority of the borescope hole open, or alternatively may extend through the length of the borescope hole.

However, certain difficulties have been discovered in the current designs. For example, the current designs may have difficulties regarding accumulation of dirt or debris proximate to the counterbore area. Accordingly, an improved inspection hole through the casing of a turbomachine and an improved plug for the inspection hole would be beneficial.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the disclosure are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the disclosure.

In one exemplary embodiment of the present disclosure, a plug for an inspection hole in a turbomachine is provided. The plug includes an attachment portion configured to attach the plug to the inspection hole in the turbomachine. The attachment portion defines a through hole. Additionally, the plug includes a tightening portion rigidly attached to the attachment portion. The tightening portion defines a through hole contiguous with the through hole of the attachment portion and defines an effective diameter. Further, the plug includes a lock nut removably attached to the tightening portion. The lock nut is configured to decrease the effective diameter of the through hole of the tightening portion when in a locked position. The plug also includes a rod positioned in the through hole of the attachment portion and in the through hole of the tightening portion. The tightening portion is configured to removably attach the rod to the tightening portion when the lock nut is in the locked position.

In another exemplary embodiment of the present disclosure, a turbomachine system is provided. The turbomachine system includes a compressor, a turbine positioned downstream of the compressor, and a combustor assembly configured between the compressor and the turbine. Additionally, the turbomachine includes an outer casing positioned around at least a portion of the compressor, the turbine, or both. The outer casing defines an outer surface and an inner surface, and defines an inspection hole extending therethrough. The inspection hole defines a coupling portion adjacent to the outer surface of the outer casing, a body extending from the coupling portion towards the inner surface of the outer casing, and a stepped end positioned adjacent to the inner surface of the outer casing. Further, the turbomachine includes a plug removably attached to the coupling portion of the inspection hole, at least a portion of the plug extending through the body of the inspection hole to the stepped end of the inspection hole.

These and other features, aspects and advantages of the present disclosure will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:

FIG. 1 is a functional diagram of an exemplary embodiment of a turbomachine of the present disclosure;

FIG. 2 is a close-up cross-sectional view of a section of the compressor of the turbomachine of FIG. 1;

FIG. 3 is a perspective view of an exemplary embodiment of a plug of the present disclosure;

FIG. 4 is a cross-sectional view of the exemplary plug of FIG. 3; and

FIG. 5 is a close-up cross-sectional view of the exemplary inspection hole and a portion of the plug depicted in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

With reference to FIGS. 1 and 2, a turbomachine 2 constructed in accordance with an exemplary embodiment of the present disclosure is provided. FIG. 1 provides a functional diagram of the turbomachine 2 and FIG. 2 provides a close-up cross-sectional view of a section 7 of the turbomachine 2 of FIG. 1. The turbomachine 2 includes a compressor 4 operatively connected to a turbine 6. Additionally, a combustor assembly 8 is fluidly connected to the compressor 4 and the turbine 6. The combustor assembly 8 may be formed from a plurality of circumferentially spaced combustors, one of which is indicated at 10. It should be appreciated, however, that in other exemplary embodiments, the combustor assembly 8 may include any other suitable arrangement of combustors 10.

The compressor 4 is also linked to the turbine 6 through a common compressor/turbine shaft 12. With this arrangement, the compressor 4 delivers compressed air to the combustor assembly 8. The compressed air may mix with a combustible fluid to form a combustible mixture. The combustible mixture may then be combusted in the combustor assembly 8 to form products of combustion that are delivered to the turbine 6 through a transition piece (not shown). The products of combustion expand through the turbine 6 to power, for example, a generator, a pump, an aircraft or the like (also not shown). Accordingly, the turbine 6 is considered to be positioned downstream from the compressor 4.

The turbomachine 2 further includes an outer casing 20 positioned around at least a portion of the compressor 4, the turbine 6, or both. For the exemplary embodiment depicted in FIG. 2, the outer casing 20 is positioned around the compressor 4 and defines an outer surface 22 and an inner surface 24. Additionally, the compressor 4 defines a plurality of stages, each of which including a plurality of circumferentially arranged rotor blades 28 configured to rotate about the shaft 12, and a plurality of stationary stator vanes 26. One of these stages is depicted in FIG. 2. The turbine 6 similarly defines a plurality of stages, each stage also including a plurality of rotor blades configured to rotate about the shaft 12 and a plurality of stationary stator vanes (not shown).

Referring specifically to FIG. 2, and as will be explained in greater detail below with reference to FIG. 5, the outer casing 20 further defines an inspection hole 50 extending therethrough and a plug 100 positioned at least partially therein. The inspection hole 50 generally includes a coupling portion 52 adjacent to the outer surface 22 of the outer casing 20, a body 56 extending from the coupling portion 52 towards the inner surface 24 of the outer casing 20, and a stepped end 58 positioned adjacent to the inner surface 24 of the outer casing 20. For the exemplary embodiment of FIG. 2, the inspection hole 50 is a stepped borescope hole configured to receive a borescope allowing a user to inspect various components within the compressor 4 without removing the outer casing 20.

The exemplary plug 100 of FIG. 2 is removably attached to the coupling portion 52 of the inspection hole 50. As shown, at least a portion of the plug 100 extends into and through the body 56 of the inspection hole 50 towards the stepped end 58 of the inspection hole 50. For the exemplary embodiment of FIG. 2, the plug 100 extends up to the stepped end 58 of the inspection hole 50. When the plug 100 is attached to the coupling portion 52 of the inspection hole 50, the plug 100 may prevent the escape of compressed air from within the compressor 4.

Referring now to FIGS. 3 and 4, the exemplary plug 100 of FIG. 2 is shown in greater detail. As shown, the plug 100 includes an attachment portion 120 configured to removably attach the plug 100 to the coupling portion 52 of the inspection hole 50. The attachment portion 120 defines a through hole 124 extending therethrough and a threaded portion 122 that corresponds to a threaded portion 54 defined by the coupling portion 52 of the inspection hole 50 (see FIG. 5). Further, the plug 100 includes a nut 119 that may assist a user in removably attaching, i.e., “screwing-in” or “un-screwing,” the plug 100 from the inspection hole 50.

It should be appreciated, however, that in other exemplary embodiments, the plug 100 may be attached to the inspection hole 50 of the casing 20 in any other suitable manner. For example, the attachment portion 120 may be press fit to the coupling portion 52, welded to the coupling portion 52, etc. In such an embodiment, the attachment portion 120 and the coupling portion 52 may not define threads 122 or 54, respectively.

The plug 100 additionally includes a tightening portion 110 and a lock nut 112. The tightening portion 110 is rigidly attached to the attachment portion 120 and defines a threaded portion 111 corresponding to a threaded portion 113 defined by the lock nut 112. In certain exemplary embodiments, the tightening portion 110, the attachment portion 120, and the nut 119 may be cast together as a single piece using any suitable material, such as stainless steel. The tightening portion 110 additionally defines a through hole 114 extending therethrough, the through hole 114 being contiguous with the through hole 124 of the attachment portion 120. Moreover, for the exemplary embodiment of FIGS. 3 and 4, the plug 100 additionally includes a first wedge ring 116 and a second wedge ring 118 positioned between a portion of the lock nut 112 and the tightening portion 110. The wedge rings 116, 118 each define an annular shape. Moreover, the first wedge ring 116 is complementary to the second wedge ring 118, and the second wedge ring 118 is complementary to a top end of the tightening portion 110. More particularly, as will be discussed below, the wedge rings 116, 118 are configured to decrease in effective diameter when pressed against the top end of the tightening portion 110 by the lock nut 112.

The plug 100 further includes a rod 102 positioned in the through hole 124 of the attachment portion 120, in the through hole 114 of the tightening portion 110, and extending through an opening in the lock nut 112. As shown, the through hole 124 of the attachment portion 120, the through hole 114 of the tightening portion 110, and the rod 102 each define a cylindrical shape. The rod 102 may be comprised of stainless steel or any other suitable material. As depicted in the FIGS., the lock nut 112 is removably attached to the tightening portion 110 and is moveable to a locked position, as shown in FIGS. 2 and 4. When the lock nut 112 is in the locked position, the lock nut 112 removably fixes the rod 102 in the through hole 114 of the tightening portion 110 and in the through hole 124 of the attachment portion 120. More particularly, for the exemplary embodiment of FIGS. 3 and 4, when in the locked position, the lock nut 112 presses the first and second wedge rings 116, 118 into the top end of the tightening portion 110, which presses the wedge rings 116, 118 radially inward and along an axial direction, A_(P), of the plug 100. Accordingly, when the lock nut 112 is in the locked position, the rod 102 is removably fixed by the friction generated by the wedge rings 116, 118 pressing against the rod 102 and the rod 102 may not move along the axial direction, A_(P), of the plug 100 relative to the tightening portion 110 or the attachment portion 120.

Referring still to FIGS. 3 and 4, the exemplary rod 102 includes a pull ring 104 positioned at a distal end 103. The pull ring 104 may assist a user in removing the rod 102 from within the tightening portion 110 and the attachment portion 120. Further, the exemplary plug 100 includes a tether 106 attaching the pull ring 104 of the rod 102 to the attachment portion 120 of the plug 100 using an attachment ring 108 encircling the attachment portion 120.

A plug 100 having such a construction may allow a user to more easily inspect aspects of the compressor 4 through the plug 100 and inspection hole 50 defined by the outer casing 20. More particularly, a user may simply loosen the lock nut 112, i.e., un-screw or move the lock nut 112 from the locked position into an open position, such as is shown in FIG. 3, and pull the rod 102 out from the through holes 114, 124 of the tightening portion 110 and attachment portion 120. Alternatively, once the plug 100 has been installed in the inspection hole 50, the first and second wedge rings 116, 118 and the lock nut 112 may be attached to or captured onto the rod 102 such that they all may be removed from the tightening portion 110 as a single unit. Regardless, however, once the rod 102 is removed (and potentially the wedge rings 116, 118 and lock nut 112), an open passage is exposed through the plug 100 and the inspection hole 50 to allow a user to, e.g., insert a borescope to inspect the compressor 4 without removing the outer casing 20. Accordingly, with such a construction, a user need not remove the entire plug 100 to examine certain aspects of the compressor 4 through the outer casing 20.

It should be appreciated, however, that in other exemplary embodiments, the plug 100 may have any other suitable construction or configuration. For example, in other exemplary embodiments, in addition to or instead of the lock nut 112 and wedge rings 116, 118, the plug 100 may include a pin configured to extend through the tightening portion 110 and rod 102 such that the rod 102 is removably attached to the tightening portion 110. Further, in other exemplary embodiments, the lock nut 112 may act as a cap to the tightening portion 110 configured to enclose the rod 102 within the tightening portion 110 of the plug 100. Moreover, in still other exemplary embodiments, the rod 102 may not include a pull ring 104 positioned at the distal end 103, and may instead include any other suitable construction for assisting a user in removing the rod 102. For example, the rod 102 may instead define a nail head with a threaded pull hole defined at the distal end 103. Such a construction may reduce the height of the plug 100 such that it fits more easily under, e.g., an insulation positioned around the casing 20. Similarly, in other exemplary embodiments, the plug 100 may not include a tether 106 or attachment ring 108, or alternatively, the attachment ring 108 and tether 106 may attach the rod 102 to the tightening portion 110 of the plug 100 or directly to the outer casing 20 of the turbomachine 2. Furthermore, in still other exemplary embodiments, the through hole 114, the through hole 124, and the rod 102 may have any other suitable shape.

Referring now to FIG. 5, a close-up view of the inspection hole 50 and a portion of the plug 100, as indicated in FIG. 2, is provided. As shown, the inspection hole 50 of the exemplary embodiment of FIG. 5 is a stepped inspection hole 50. More particularly, the inspection hole 50 includes a first step 57 between the coupling portion 52 and the body 56, and a second step, a stepped end 58, positioned at the end of the body 56 and adjacent to the inner surface 24 of the outer casing 20. The geometry of the body 56 of the inspection hole 50 is complementary to the geometry of the rod 102 of the plug 100, and defines a length, L_(B), and a diameter, D_(B). More particularly, a diameter of the rod, D_(R), is approximately equal to the diameter of the body, D_(B). In addition, the stepped end 58 defines a diameter, D_(S), that is less than the diameter of the body, D_(B), and similarly is less than the diameter of the rod, D_(R). Accordingly, the size of the inspection hole 50 at the stepped end 58 is less than the size of the inspection hole 50 at the body 56. Thus, the stepped end 58 may prevent the rod 102 of the plug 100 from extending past the inner surface 24 of the outer casing 20 and into a flowpath of the compressor 4. Such a construction may minimize the risk of the rod 102 damaging the compressor 4 by contacting one or more of the rotor blades 28.

In addition, due to the position of the stepped end 58 of the inspection hole 50 proximate to the inner surface 24 of the outer casing 20, the stepped end 58 may allow the rod 102 to be substantially inserted into the inspection hole 50. Such a construction may minimize the amount of open space in the inspection hole 50 during operation of the compressor 4 and the turbomachine 2. By minimizing the amount of open space in the inspection hole 50, the risk of any acoustic resonance that may otherwise be generated during operation may also be minimized. In certain exemplary embodiments, the risk of acoustic resonance may be so minimized when the stepped end 58 of the inspection hole 50 is positioned within about L_(S) inches from the inner surface 24 of the outer casing 20, wherein L_(S) is less than or equal to about two thirds of the diameter of the body, D_(B), of the inspection hole 50. For example, in such an embodiment, the diameter of the body, D_(B), may be one (1) inch and L_(S) may be less than or equal to about two thirds (⅔) of an inch.

It should be appreciated, however, that in other exemplary embodiments, the inspection hole 50 may have any other suitable shape or construction. For example, the first step 57, the stepped end 58, or both may define an angled slope where it transitions between the coupling portion 52 and body 56, or between the body 56 and stepped end 58. Additionally, in other exemplary embodiments, the stepped end 58 may have any suitable shape or geometry for preventing the rod 102 from extending into the flowpath of the compressor 4 or turbine 6. For example, the body 56 of the inspection hole 50 may extend to the inner surface 24 of the outer casing 20, and the stepped end 58 may include one or more notches extending into the body 56 of the inspection hole 50 proximate to the inner surface 24 of the outer casing 20. Moreover, in other exemplary embodiments, the stepped end 58 may be located at any suitable position within the inspection hole 50. For example, in other exemplary embodiments, L_(S) may be greater than about two thirds of the diameter of the body, D_(B).

It should also be appreciate that in still other exemplary embodiments, the inspection hole 50 may not be a borescope hole, and instead may be a clearanceometer hole. More particularly, the inspection hole 50 may be configured to receive a device for determining the clearance of the tips of the rotor blades 28 within the compressor 4 or turbine 6 of the turbomachine 2, or for any other suitable purpose. Additionally, in still other exemplary embodiments, the inspection hole 50 may be defined in the outer casing 20 positioned around the turbine 6 of the turbomachine 2, and/or there may be a plurality of inspection holes 50 defined by the outer casing 20 proximate to two or more stages of the compressor 4, the turbine 6, or both. In such an exemplary embodiment, due to the particular requirements of the individual inspection holes 50 defined by the outer casing 20 proximate to different stages of the compressor 4, the turbine 6, or both, the length of the body, L_(B), of the inspection holes 50 may vary. Accordingly, the length of the rods 102 in the plugs 100 may also vary. Regardless, however, due to the geometry of the inspection holes 50, i.e., the size and geometry of the stepped ends 58, the risk of inserting a rod 102 that is too long for the inspection hole 50, such that it extends into the flowpath of the compressor 4, the turbine 6, or both and potentially causes damage, is minimized. Accordingly, the rods 102 from the plurality of plugs 100 in such an exemplary embodiment may be interchangeable.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. 

What is claimed is:
 1. A plug for an inspection hole in a turbomachine, comprising: an attachment portion configured to attach the plug to the inspection hole in the turbomachine, the attachment portion defining a through hole; a tightening portion rigidly attached to the attachment portion, the tightening portion defining a through hole contiguous with the through hole of the attachment portion; a lock nut removably attached to the tightening portion and moveable to a locked position; and a rod removably fixed in the through hole of the attachment portion and in the through hole of the tightening portion when the lock nut is in the locked position.
 2. The plug of claim 1, wherein the through hole of the attachment portion, the through hole of the tightening portion, and the rod each define a cylindrical shape.
 3. The plug of claim 1, wherein the plug is configured to be positioned in an inspection hole defined in an outer casing around a compressor of the turbomachine.
 4. The plug of claim 1, wherein the plug further comprises one or more wedge rings positioned between a portion of the lock nut and the tightening portion, wherein the one or more wedge rings press against the rod when the lock nut is in the locked position such that the rod is removably fixed in position.
 5. The plug of claim 1, wherein the inspection hole is a borescope hole.
 6. The plug of claim 1, wherein the rod comprises a pull ring positioned at a distal end of the rod.
 7. The plug of claim 1, further comprising a tether configured to attach the attachment portion, the tightening portion, or both to the rod.
 8. The plug of claim 1, wherein the rod is comprised of stainless steel.
 9. A turbomachine system comprising: a compressor; a turbine positioned downstream of the compressor; a combustor assembly configured between the compressor and the turbine; an outer casing positioned around at least a portion of the compressor, the turbine, or both and defining an outer surface and an inner surface, wherein the outer casing defines an inspection hole extending therethrough and the inspection hole defines a coupling portion adjacent to the outer surface of the outer casing; a body extending from the coupling portion towards the inner surface of the outer casing; and a stepped end positioned adjacent to the inner surface of the outer casing; and a plug removably attached to the coupling portion of the inspection hole, at least a portion of the plug extending into the body of the inspection hole towards the stepped end of the inspection hole.
 10. The system of claim 9, wherein the inspection hole is defined in the outer casing positioned around the compressor of the turbomachine.
 11. The system of claim 9, wherein the body of the inspection hole defines a diameter and the stepped end of the inspection hole defines a diameter, and wherein the diameter of the stepped end is less than the diameter of the body.
 12. The system of claim 9, wherein the stepped end is positioned within about L inches from the inner surface of the outer casing, wherein L is less than or equal to about two thirds of the diameter of the body of the inspection hole.
 13. The system of claim 9, wherein the inspection hole is a borescope hole.
 14. The system of claim 9, further comprising a plurality of inspection holes in the outer casing and a plurality of plugs positioned in the inspection holes, the plurality of inspection holes positioned proximate to two or more stages defined by the compressor portion, wherein the plurality of plugs each include a rod, and wherein the rods from the plurality of plugs are interchangeable.
 15. The turbomachine system of claim 9, wherein the plug further comprises: an attachment portion defining a through hole, the attachment portion removably attached to the coupling portion of the inspection hole; a tightening portion rigidly attached to the attachment portion of the plug, the tightening portion defining a through hole contiguous with the through hole of the attachment portion of the plug; a lock nut removably attached to the tightening portion and moveable to a locked position; and a rod removably fixed in the through hole of the attachment portion and in the through hole of the tightening portion when the lock nut is in the locked position.
 16. The system of claim 15, wherein the diameter of the stepped end is less than a diameter of the rod.
 17. The system of claim 15, wherein the rod includes a pull ring positioned at a distal end.
 18. The system of claim 15, wherein the plug further comprises a tether configured to attach the attachment portion, the tightening portion, or both to the rod.
 19. The system of claim 15, wherein the plug further comprises one or more wedge rings positioned between a portion of the lock nut and the tightening portion, wherein the one or more wedge rings press against the rod when the lock nut is in the locked position such that the rod is removably fixed in position.
 20. The system of claim 15, wherein the through hole of the attachment portion, the through hole of the tightening portion, and the rod each define a cylindrical shape. 